Effect of square opening area on the shock wave and spontaneous ignition of high-pressure hydrogen released into a tube
An experimental study investigated the shock wave propagation characteristics and spontaneous ignition of high-pressure hydrogen released into the tube through releasing ports with different opening areas.Three sizes of square openings are considered,with an area of 113 mm2(opening ratioλ=4/5),75 mm2(λ=2/3),and 49 mm2(λ=1/2).The results show that reducing the opening ratio weakens the intensity and speed of the shock wave in the tube,further inhibiting the development of the shock wave propagating downstream.Moreover,the minimum burst pressure required for hydrogen spontaneous ignition increases with the decreasing opening ratio.When the opening ratio decreases,the overall flame intensity and propagation speed of hydrogen spontaneous ignition decrease.Especially when the opening ratio is small(λ=1/2),when the burst pressure increases,the maximum flame intensity in the tube does not have an apparent increase,indicating that the reduction of the opening ratio has an inhibition effect on the overall flame intensity.